Because LED has the advantages of saving power, long lifetime, environmental protection, etc., various new LED bulb products are produced to replace traditional incandescent bulb and halogen bulb. Traditional capsule bulb is a small lighting bulb, for example, G4 or G9 bulbs belong to capsule bulb. Taking G9 bulb for example, it is used for modern European crystal chandelier, but the whole weight that the chandelier can take is limited. According to rules of lighting industry international standards BS EN60061-1-1993+A46-2011, there are specific demands for the weight of G9 bulb. In general, the weight of G9 bulb cannot exceed 12 gram.
Most LED bulbs for replacing G9 halogen bulb (hereinafter“G9 LED bulb”) in the present market are using direct current (DC) to drive the bulbs, which needs specific driving circuits. In the meanwhile, because of the light-emitting directionality of the LED, G9 LED bulb needs some special mechanical structures for accommodating light source like LED to make LED face different directions to generate omnidirectional light-emission pattern similar to what traditional G9 halogen bulb produces. As a consequence, G9 LED bulb has a larger volume, complicated manufacture and assemble processes, and high cost. Besides, the heat dissipation of LED is also the key factor to determine the quality of G9 LED bulb. If the heat dissipation efficiency is not good, it significantly decreases the lifetime of the product.
Therefore, the issues like the heat dissipation, light-emission pattern, cost of manufacture and the limitation of 12 gram weight need to be considered when making G9 LED bulb. However, based on current technology, it is difficult to resolve everything. For example, current technology usually has no market competitiveness due to high cost of G9 LED bulb, or has the issues about small lighting angle and short lifetime.